1. Field of the Invention
The present invention is directed to exchanging e-mail messages involving a mobile data communications device (“mobile device”), and more particularly to exchanging secure e-mail messages involving a mobile device.
2. Description of the Related Art
There are many solutions for exchanging information between host systems and mobile devices. These systems all follow simple encoding methods for delivering a shortened version of the original message to the wireless mobile device, keeping in mind the limited memory and display capabilities of the device. However, there is a lack of focus and attention being paid to the problems of delivering S/MIME message to mobile devices. Currently there are no known systems that try to delivery the entire S/MIME message to the mobile device. This is because the bandwidth and battery limitations when using wireless devices makes it impossible to create such a solution without performing any pre-processing on the message. One major problem is that S/MIME messages are too large to send effectively to the mobile device. If the entire S/MIME message is sent, it could use excessive amounts of memory and battery power just for a single message. Considering the time necessary for reception, the memory required for storage and the battery required to handle the RF exchange, a product that tried to support direct S/MIME would be unusable to the average business user. The second problem is that there are no public key servers accessible to wireless networks and wireless devices. As a result the use of public key crypto operations is very difficult and requires heavy caching operations to eliminate the Public Key Infrastructure (PKI) requirements.
In the area of exchanging secure e-mail there are additional problems that include (1) the inability for mobile devices to retrieve public encryption keys from Public Key Infrastructures (PKIs) to encrypt messages being sent from the mobile device, (2) the inability to retrieve public keys on received messages that are signed, (3) the inability to deal with very large Certificate Revocation Lists (CRLs) on small devices and (4) the time delay on mobile devices with slower CPUs to perform complex math calculations involved with public key encryption algorithms. These problems and others result in a poor and frustrating user experience when trying to exchange S/MIME-based e-mail messages with other companies.
Therefore there remains a need for a system and method for processing secure mail so that S/MIME messages can be exchanged with mobile devices. There also remains a method for leveraging the processor power of the host system to enable a better user experience when exchanging S/MIME messages with outside correspondents.